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A '''geosynchronous transfer orbit''' or '''geostationary transfer orbit''' ('''GTO''') is a [[Hohmann transfer orbit]] used to reach [[geosynchronous orbit|geosynchronous]] or [[geostationary orbit]].<ref name=smad2ed>
Larson, Wiley J. and James R. Wertz, eds. Space Mission Design and Analysis, 2nd Edition. Published jointly by Microcosm, Inc. (Torrance, CA) and Kluwer Academic Publishers (Dordrecht/Boston/London). 1991.</ref>
It is a highly [[ellipse|elliptical]] Earth [[orbit]] with an [[apogee]] of {{convert|42164|km|mi|-3|abbr=on}},<ref>
{{cite book |title=Fundamentals of Astrodynamics and Applications |last=Vallado |first=David A. |year=2007 |publisher=Microcosm Press |location=Hawthorne, CA  |pages=31 }}
</ref> or {{convert|35786|km|mi|-3|abbr=on}} above sea level, which corresponds to the geostationary (GEO) altitude.  The [[argument of perigee]] is such that apogee occurs on or near the equator. Perigee can be anywhere above the atmosphere, but is usually restricted to a few hundred kilometers above the Earth's surface to [[Oberth_effect|reduce launcher delta-V (<math>\Delta</math>V)]] requirements and to [[Orbital_decay|limit the orbital lifetime of the spent booster]].
 
The [[inclination]] of a GTO is the angle between the orbit plane and the Earth's [[equator|equatorial plane]]. It is determined by the [[latitude]] of the launch site and the launch [[azimuth]] (direction). The inclination and eccentricity must both be reduced to zero to obtain a geostationary orbit. If only the [[Orbital eccentricity|eccentricity]] of the orbit is reduced to zero, the result is a geosynchronous orbit. Because the <math>\Delta</math>V required for a plane change is proportional to the instantaneous velocity, the inclination and eccentricity are usually changed together in a single manoeuvre at apogee where velocity is lowest.  
 
==Technical description==
The required <math>\Delta</math>V for an inclination change at either the ascending or descending [[orbital node|node]] of the orbit is calculated as follows:<ref>Curtis, H.D. (2010) Orbital Mechanics for Engineering Students, 2nd Ed. Elsevier, Burlington, MA, pp. 356-357.</ref>
 
:<math>\Delta V = 2 V \sin \frac{\Delta i}{2}</math>
 
For a typical GTO with a [[semimajor axis]] of 24,582&nbsp;km, [[perigee]] velocity is 9.88&nbsp;km/s and [[apogee]] velocity is 1.64&nbsp;km/s, clearly making the inclination change far less costly at apogee.  In practice, the inclination change is combined with the orbital circularization (or "[[apogee kick]]") burn to reduce the total <math>\Delta</math>V for the two maneuvers. The combined <math>\Delta</math>V is the vector sum of the inclination change <math>\Delta</math>V and the circularization <math>\Delta</math>V, and as the sum of the lengths two sides of a triangle will always exceed the remaining side's length, total <math>\Delta</math>V in a combined maneuver will always be less than in two maneuvers. The combined <math>\Delta</math>V can be calculated as follows:<ref>Curtis, H.D. (2010) Orbital Mechanics for Engineering Students, 2nd Ed. Elsevier, Burlington, MA, pp. 356-357.</ref>
 
:<math>\Delta V = \sqrt{ V_{t,a}^{2} + V_{GEO}^{2} - 2 V_{t,a} V_{GEO} \cos \Delta i}</math>
where <math>V_{t,a}</math> is the velocity magnitude at the apogee of the transfer orbit and <math>V_{GEO}</math> is the velocity in GEO.
 
==Other considerations==
 
Even at apogee, the fuel needed to reduce inclination to zero can be significant, giving equatorial launch sites a substantial advantage over those at higher latitudes. [[Baikonur Cosmodrome]] in [[Kazakhstan]] is at 46 degrees north latitude. [[Kennedy Space Center]] is at 28.5 degrees north. [[Guiana Space Centre]], the [[Ariane (rocket family)|Ariane]] launch facility, is at [[5th parallel north|5 degrees north]]. [[Sea Launch]] launches from a floating platform directly on the equator in the [[Pacific Ocean]].
 
[[Expendable launch system|Expendable]] launchers generally reach GTO directly, but a spacecraft already in a low Earth orbit ([[Low Earth orbit|LEO]]) can enter GTO by firing a [[rocket]] along its orbital direction to increase its velocity. This was done when geostationary spacecraft were launched from the [[space shuttle]]; a "perigee kick motor" attached to the spacecraft ignited after the shuttle had released it and withdrawn to a safe distance.
 
Although some launchers can take their payloads all the way to geostationary orbit, most end their missions by releasing their payloads into GTO. The spacecraft and its operator are then responsible for the manoeuvre into the final geostationary orbit.  The five-hour coast to first apogee can be longer than the battery lifetime of the launcher or spacecraft, and the manoeuvre is sometimes performed at a later apogee or split among multiple apogees. The solar power available on the spacecraft supports the mission after launcher separation. Also, many launchers now carry several satellites in each launch to reduce overall costs, and this practice simplifies the mission when the payloads may be destined for different orbital positions.
 
Because of this practice, launcher capacity is usually quoted as spacecraft mass to GTO, and this number will be higher than the payload that could be delivered directly into GEO.
 
For example, the capacity (adapter and spacecraft mass) of the [[Delta IV rocket|Delta IV]] Heavy is:<ref>United Launch Alliance, ''Delta IV Launch Services User's Guide'' June 2013, pp. 2-10, Figure 2-9; http://www.ulalaunch.com/site/docs/product_cards/guides/Delta%20IV%20Users%20Guide%20June%202013.pdf accessed 2013 July 27</ref>
*GTO 14,220 kg (185&nbsp;km x 35,786&nbsp;km at 27.0 deg inclination), theoretically more than any other currently available launch vehicle (it is not known to have flown with such a payload yet)
*GEO 6,750 kg
 
If the manoeuvre from GTO to GEO is to be performed with a single impulse, as with a single solid rocket motor, apogee must occur at an equatorial crossing and at synchronous orbit altitude. This implies an argument of perigee of either 0 or 180 degrees. Because the argument of perigee is slowly perturbed by the oblateness of the Earth, it is usually biased at launch so that it reaches the desired value at the appropriate time (for example, this is usually the sixth apogee on [[Ariane 5]] launches<ref>ArianeSpace, ''Ariane 5 User's Manual'' Issue 5 Revision 1, 2011 July, pp. 2-13, http://www.arianespace.com/launch-services-ariane5/Ariane-5-User%27s-Manual.asp accessed 2013 July 27</ref>). If the GTO inclination is zero, as with Sea Launch, then this does not apply. (It also would not apply to an impractical GTO inclined at 63.4 degrees; see [[Molniya Orbit]].)
 
The preceding discussion has primarily focused on the case where the transfer between LEO and GEO is done with a single intermediate transfer orbit.  More complicated trajectories are sometimes used.  For example, the [[Proton_(rocket)#Proton_M|Proton M]] uses a set of three intermediate orbits, requiring five upper stage rocket firings, to place a satellite into GEO from the high-inclination site of [[Baikonur Cosmodrome]], in [[Kazakhstan]].<ref>International Launch Services, ''Proton Mission Planner's Guide'' Rev. 7 2009 November, pp. 2-13, Figure 2.3.2-1, http://www.ilslaunch.com/sites/default/files/pdf/Proton%20Mission%20Planner%27s%20Guide%20Revision%207%20%28LKEB-9812-1990%29.pdf accessed 2013 July 27</ref> Because of Baikonur's high latitude and range safety considerations that block launches directly east, it requires less delta-v to transfer satellites to GEO by using a [[Supersynchronous orbit|supersynchronous transfer orbit]] where the apogee (and the maneuver to reduce the transfer orbit inclination) are at a higher altitude than 35,786km, the geosynchronous altitude.  Proton even offers to perform a supersynchronous apogee maneuver up to fifteen hours after launch. <ref>ibid. Appendix F.4.2, page F-8</ref>
 
==See also==
{{Portal|Spaceflight}}
* [[Astrodynamics]]
* [[Low Earth orbit]]
* [[List of orbits]]
 
== References ==
{{reflist}}
 
{{orbits}}
 
[[Category:Astrodynamics]]
[[Category:Earth orbits]]

Revision as of 12:22, 17 February 2014

Almost everyone is today aware that life-style illnesses are a leading killer in today's globe plus now the query on most women's notice is: are there diets which function for ladies? If you find oneself asking this query then you are not alone in the quest for diets that work quick for ladies.

Be consistent with the diet - in the event you want to get rid of fat plus keep it off, then you need to eat sensibly daily...and exercise frequently. At the finish of the day, quickly diets that work should promote healthy practices - because it might better a health!

How countless occasions have you heard a friend or personally experienced the breaking of the diet. Many folks usually provide up on conventional diet plans considering it takes too lengthy to experience the results they are hunting for. Partial meal replacements usually assist you to lose fat quicker specifically if it is actually used inside addition to usual exercise.

The Hallelujah Diet includes an optional transition phase for those persons who feel that their bodies want time to adapt to the fresh regime and effectively detoxify their systems. This diet excludes all foods of animal origin with a single exception, honey. The just foods enabled are fruits, legumes, and certain nuts plus grains. Furthermore, a full 85% of your food intake must be raw, which, inside the eyes of this diet, is food as it was built by God. Cooked foods will include coffee (is the fact that a food?), infusions, natural juices, soups, cereals, beans, and fruit.

The pineapple diet is good for losing abdomen plus lower belly plus being a fairly delicious exotic fruit of the tropics is great for reducing significant blood pressure for people suffering from this condition. If you wish To lose weight fast without exercising, you are able to try these diets to lose fat rapidly plus blend a bit of pineapple in a daily menu plus healthy eating minimize those additional kilos.

It has been medically proven that there are cardiovascular benefits to a glass of wine, a beer or perhaps a cocktail by raising the wise cholesterol degrees and thinning the blood. The wellness and diet issues are raised by drinking alcohol to excess.

I eat a range of food whenever I'm dieting to avoid elements from getting boring. There are tons of healthy dishes out there plus I can try to add any healthy dishes when I may think of them. In the mean time here are my favorite healthy recipes which I like to consume at least a couple of times a week.